Slab formwork systems

ABSTRACT

A slab formwork system for casting ceilings has panel support beams underlying and supporting formwork panels; and shores supporting the panel support beams. The panel support beams have upwardly facing top surfaces with upwardly open, longitudinally extending recesses and resiliently deformable strips of elastomeric material extending along the recesses. The formwork panels having marginal edge undersurface portions mounted on the panel support surfaces and downwardly protruding panel retainer projections embedded in the resiliently deformable strips. The formwork panels each have a pair of parallel, elongate intermediate members extending between and interconnecting parallel elongate side members and a sheet of material supported on the side and intermediate members, and the side members have undersides formed with a longitudinally extending, downwardly open recesses. Connecting clips retained in the downwardly open recesses are engaged with the support beams to secure the formwork panels to the support beams. The panel support beams are telescopically longitudinally adjustable to allow corresponding variation of the spacings of the shores which have dropheads each having a first component forming a prophead extending between an adjacent pair of the formwork panels and a second component in supporting engagement with the formwork panels. The first and second components have mutually engaged screw threads allowing the second component to be lowered relative to the first component for releasing the formwork panels.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to slab formwork systems and is useful in particular, but not exclusively, for formwork systems for use in casting concrete ceilings.

2. Description of the Related Art

In the construction of concrete buildings, it is known to employ, for the casting of ceilings, a slab formwork comprising panel support beams mounted on shores and panels supported on the panel support beams. It is further known to provide the shores with dropheads, which support the beams and which also have heads projecting between the panels. In use, after a concrete slab has been cast on the panels and the concrete of the slab has sufficiently hardened, parts of the dropheads carrying the beams and panels can be released for movement downwardly relative to the shores, thereby allowing the beams and the panels to the withdrawn downwardly from the newly cast concrete. The heads of the dropheads remain in position to support the concrete. An example of such a prior art formwork system is disclosed in U.S. Pat. No. 5,614,122, issued Mar. 25, 1997 to Artur Schwoerer.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, there is provided a slab formwork system with panel support beams underlying and supporting formwork panels and shores supporting the panel support beams, the panel support beams having upwardly facing panel support surfaces extending along the panel support beams, upwardly open, longitudinally extending recesses between the panel support surfaces and resiliently deformable strips of elastomeric material extending along the recesses. The panels have marginal edge undersurface portions mounted on the panel support surfaces and downwardly protruding panel retainer projections embedded in the resiliently deformable strips.

The embedding of the panel retainer projections into the resiliently deformable strips counteracts undesired displacement of the panels longitudinally of the panel support beams and thereby substantially stabilizes the assembly of the panels on the beams and shores.

The panel retainer projections of adjacent pairs of the formwork panels engage in respective ones of resiliently deformable strips and are tapered so as to urge the adjacent pairs of panels towards one another as the panel retainer projections become embedded in the strips. Consequently, as the panels are mounted on the panel support beams, the panels at opposite sides of each panel support beam are automatically drawn together so as to reduce or even effectively eliminate any gaps between opposed edges of adjacent panels.

The formwork panels each have a pair of parallel, elongate side members, elongate intermediate members extending between and interconnecting the side members and a sheet of material supported on the side and intermediate members, and the side members have undersides formed with a longitudinally extending, downwardly open recesses. Connecting clips retained in the downwardly open recesses are engaged with the panel support beams to secure the formwork panels to the support beams.

The panel support beams are telescopically longitudinally adjustable to allow corresponding variation of these spacings of the shores, which have dropheads and the dropheads each have a first component forming a prop extending between an adjacent pair of the formwork panels and a second component in supporting engagement with the formwork panels. The first and second components having mutually engaged screw threads allowing the second component to be lowered gradually and gently, by an easily controlled amount, relative to the first component for releasing the formwork panels without damage to the components of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood from the following description of an embodiment thereof given, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 shows a view in perspective of a partially-completed slab formwork according to a preferred embodiment of the present invention;

FIG. 2 shows a broken-away view of a pair of beams mounted on a dropheads forming part of the slab formwork system of FIG. 1;

FIG. 3 shows a view, taken at right angles relative to that of FIG. 3, and illustrating parts of panel support beams and panels supported by the drophead;

FIG. 4 shows a view in perspective of the drophead of FIGS. 3 and 4;

FIG. 5 shows a view in perspective of a displaceable component of the drophead of FIG. 4;

FIGS. 6, 7 and 8 show views in side elevation of a panel support beam forming part of the slab formwork system of FIG. 1 in retracted, partly extended and fully extended conditions, respectively;

FIGS. 9 and 10 show views in perspective of an end component of the telescopic panel support beam and an end portion of the support beam shown in FIGS. 6, 7 and 8;

FIG. 11 shows a view taken in vertical longitudinal cross-section through the telescopic panel support beam of FIGS. 6, 7 and 8;

FIG. 12 shows a broken-away view of parts of one of the panels of the slab formwork system of FIG. 1;

FIG. 13 shows a view in vertical cross-section through adjacent edge portions of a pair of panels mounted on an upper portion of a panel support beam in the slab formwork system of FIG. 1; and

FIGS. 14A and 14B show views in perspective of a connecting clip and a panel retainer projection, respectively, of the apparatus of FIG. 14; and

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1 of the accompanying drawings, there is illustrated a partly-completed slab formwork according to a preferred embodiment of the invention, which is indicated generally by reference numeral 10.

The slab formwork system 10 has panel support beams 12, which as described in greater detail below are of hollow cross-section and longitudinally telescopic, arranged in parallel rows and mounted on dropheads, indicated generally by reference numerals 14, which in turn are mounted on shores 16. Filler beams 18, which may conveniently be formed of 2×4″ lumber, extend at right angles to the panel support beams 12 between the parallel rows of panel support beams 12 and are supported at opposite ends of the beams on the dropheads 14. Panels 20 are mounted on the panel support beams 12 between the filler beams 18.

FIG. 2 shows the ends of a pair of the filler beams 18 mounted on one of the dropheads 14, which is described in greater detail below with reference to FIGS. 2-5 of the accompanying drawings.

The drophead 14 comprise is a first component, indicated generally by reference numeral 22, which is fixed relative to its respective shore 16, and a second component, which is indicated generally by reference 24 and illustrated in FIG. 5, and which is vertically displaceable relative to the first component 22, as described below.

The second component 24 of the drophead 14, as shown in FIG. 5, has a tube or sleeve 26 which, at its upper end, is provided with a pair of support brackets, indicated generally by reference numeral 28 projecting from opposite sides of the sleeve 26. The second component 24 also has two pairs of parallel bearing plates which are indicated generally by reference numerals 30, and which project from opposite sides of the sleeve 26 at right angles to the support brackets 28.

The first component 22 of the drophead 14 has a tubular portion 32 welded to a base plate 34, and a screw 36 extending upwardly from the tubular portion 32. The base plate 34 is fixed to the top of the shore 16 by nut-and-bolt fastener 33, as shown in FIG. 3. A T-shaped prophead, indicated generally by reference 38, is mounted on the top of the screw 36 and is formed by a vertical member 40 extending from the screw 36 and welded to a horizontal member 42 to form a T-bar, the vertical and horizontal members 40 and 42 being formed by metal tubes of rectangular cross-section.

A nut 44 in threaded engagement with the screw 36 is formed with handles 46 to facilitate rotation of the nut 44 relative to the screw 36. The nut 44 is in sliding contact with a bearing ring 48 at the lower end of the sleeve 26.

As can be seen in FIG. 2, the filler beams 18 extend from opposite ends of the horizontal member 42 of the prop head 38 and the tops of the filler beams 18 are flush with the top of the prop head 38. The vertical member 40 of the prophead 38 is provided with laterally protruding jam plates 45, which are spaced downwardly from the horizontal member 42, and project at right angles relative to the horizontal member 42. These jam plates 45 abut the top of the sleeve 26 when the top of the prophead 38 is flush with the tops of the filler beams 18. As shown in FIG. 1, the filler beams 18 extend between adjacent pairs of the panels 20.

FIG. 3, which shows a view of the drophead 14 taken at right angles to that of FIG. 2, illustrates a pair of the panel support beams 12, which are each provided at opposite ends with beam extension members 50 (see FIGS. 6-8), supported on the bearing plates 30 at opposite sides of the sleeve 26, with the panel support beams 12 extending at right angles to the filler beams 18.

More particularly, with reference to FIGS. 6-8, the beam extension members 50 are telescopically engaged in the beams 12 and are each formed with five transverse bolt holes 52. Pins 54 extend through outer ends of the beam extension members 50 and rest on the bearing plates 32 to support the beam 12 on the drophead 14. As can be seen from FIG. 5, each bearing plate 30 is formed with and upwardly open recesses 56 for receiving and retaining the pins 54.

The panel support beams 12 are also formed with transverse bolt holes 58, through which bolts 60 can be inserted, these bolts 60 also extending through corresponding bolt holes 52 in the beam extension members 50 to retain the latter in position relative to the panel support beams 12. By this means, the beam extension members 50 can be drawn into the beams 12 into retracted positions, as shown in FIGS. 6 and 9, or into partly extended positions, as shown in FIG. 7 or into fully extended positions, as shown in FIGS. 8 and 10, and locked in these positions.

FIG. 3 also shows the panels 20 supported on the panel support beams 12, with the filler beams 18 extending between adjacent panels 20 between of the drophead 14 and with one of the brackets 28 extending between and upwardly from the tops of the beam extension members 52 support one of the filler beams 18.

FIGS. 9 and 10 show broken-away views of an end portion 66 of one of the support beams 12, which is reinforced by longitudinally extending, transverse internal webs 68. The webs 68 are located above and below, respectively, the bolt holes 58 to avoid obstructing the bolts 60.

As shown in FIGS. 13 and 14, the panel support beam 12 is formed with spaced side walls numeral 80 connected by upper and lower webs 82 and 84. In addition, the panel support beam 12 has, at its top and bottom, webs 86 connecting the sidewalls 80 and the top and bottom webs 82 and 84 to laterally outwardly projecting flanges 88 and laterally inwardly extending flanges 91, and the flanges 91 define an upwardly open, longitudinally extending recess 92 in the top of the panel support beam 12 and also in the bottom of the panel support beam 12. In the uppermost recess 92, there is provided a resiliently deformable insert or strip 94 of elastomeric material, and the inwardly extending flanges 90 are formed with steps 96 engaging and retaining the resiliently deformable strip 94 within the uppermost recess 92.

As can be seen from FIGS. 9 and 10, the beam extension member 50 has an upper portion, indicated generally by reference numeral 95, which has a cross-sectional shape similar to that of a corresponding upper portion of the support beams 12, i.e. is formed of portions which correspond to the upper web 82, webs 86, flanges 88 and 91, recess 92 and lip 130, and which for convenience are indicated by corresponding reference numerals with the suffix “A” added. An insert 94A of elastomeric material, corresponding in cross-sectional shape to the elastomeric material strip 94, is inserted into the recess 92A.

The panels 20 are formed of parallel, elongate side members in the form of extrusions 100, which are interconnected by elongate intermediate members, in the form of extrusions 102, and plywood sheets 104 are mounted on the extrusions 100 and 102. The extrusions 100, as shown in FIG. 12, have recesses 106, which have opposite side walls 107 and are downwardly open between opposed flanges 108.

At the adjacent edges ofadjacent panels 20, the recesses 106 receive panel retainer projections 110, which are secured in position relative to the extrusions 100 by bolts 112 extending through the sidewalls 107 of the recesses 106 and through the panel retainer projections 110.

The panel retainer projections 110 are formed as rectangular blocks 111 (FIG. 14A) having downwardly protruding nose portions 102 which, as shown in FIG. 13, press into and are thereby embedded in the resiliently deformable strip 94. This embedding of the nose portions 102 of the panel retainer projections 110 in the resiliently deformable strip 94 prevents the panels 20 from sliding laterally of the panels, i.e. longitudinally of the panel support beams 12, and also ensures stability of the assembly of the panels 20 and the beams 12. Also, the engagement of the panel retainer projections 110 in the recesses 92, between the flanges 90, secures the parallel rows of the beams 12 relative to one another. The nose portions 102 have flat, vertical opposed faces 114 (FIG. 14A), which are located adjacent one another, and opposite outwardly and upwardly inclined faces 116 at their sides opposite from the faces 114. The faces 114 and 116 merge smoothly with convexly curved lowermost surface portions 118. As a result of the inclination of the surfaces 114, the nose portions 102 are downwardly tapered so as to urge adjacent pairs of the panels 20 toward one another as the nose portions 102 of the panel retainer projections 110 are inserted into the recesses 92 and thereby pressed into and embedded in the resiliently deformable strip 94.

In addition, the provision of the resiliently deformable strip 94 in the recess 92 at the top of the beam 12 prevents the entry of concrete past the flanges 90 into the recess 92, during use of the slab formwork system 10, thereby avoiding any necessity to remove such concrete after the casting of a slab in order to prepare the panel support beam 12 for a new casting operation.

Referring now to FIGS. 13 and 14B, there is shown a connecting clip indicated generally by reference numeral 120, which is formed by a retainer member 122 which is U-shaped and which is retained by a bolt 124 and a nut 126. The bolt has a rectangular-elliptical head 128, which is received in the recess 106 of the extrusion 100, so that on tightening of the nut 126, the retainer member 122 is clamped into engagement with the underside of the extrusion 100 and with the panel support beam 12. More particularly, the outwardly extending flanges 88 of the panel support beam 12 are each formed, at their outermost ends, with a depending lip 130, and the retainer member 122 has a flange 132 which engages between one of the lips 130 and the adjacent flange 86 of the panel support beam 12. Consequently, by means of the connecting clip 120, the associated panel 20 is locked in position relative to the panel support beam 12.

As will be readily apparent to those skilled in the art, various modifications may be made in the above-described embodiment of the present invention within the scope of the appended claims. 

1. A slab formwork system, comprising: formwork panels; panel support beams underlying and supporting the formwork panels; and shores supporting the panel support beams; the panel support beams having upwardly facing top surfaces; upwardly open, longitudinally extending recesses between the top surfaces and resiliently deformable strips of elastomeric material extending along the recesses; and the formwork panels downwardly protruding panel retainer projections embedded in the resiliently deformable strips.
 2. A slab formwork system has claimed in claim 1, wherein the panel retainer projections are tapered so as to urge adjacent pairs of the panels towards one another as the panel retainer projections become embedded in the strips.
 3. A slab formwork system has claimed in claim 1, wherein the beams have pairs of flanges spaced apart by gaps, the recesses being upwardly open through the gaps, and wherein the gaps are closed by the resiliently deformable strips.
 4. A slab formwork system as claimed in claim 3, wherein the flanges are shaped, within the recesses, to interfit with and retaining the resiliently deformable strips.
 5. A slab formwork system as claimed in claim 1, including connectors securing the formwork panels to the panel support beams.
 6. A slab formwork system as claimed in claim 5, wherein the panel support beams have laterally outwardly projecting flanges and the contactors comprise connector strips secured to the formwork panels and engaging the outwardly projecting flanges.
 7. A slab formwork system as claimed in claim 1, wherein the formwork panels have elongate side members formed as extrusions, the extrusions have longitudinal, downwardly open recesses and the panel retainer projections extend from ends of the downwardly open recesses.
 8. A slab formwork system as claimed in claim 7, including connectors engaged in the downwardly open recesses and in retaining engagement with the panel support beams.
 9. A slab formwork system, comprising: formwork panels; the formwork panels each having a pair of parallel, elongate side members, elongate intermediate members extending between and interconnecting the side members and a sheet of material supported on the side and intermediate members; the side members having undersides formed with a longitudinally extending, downwardly open recesses: support beams carrying the panels; and connecting clips retained in the downwardly open recesses and engaged with the support beams to secure the formwork panels to the support beams.
 10. A slab formwork system as claimed in claim 9, wherein the connecting clips include bolts having heads retained in the downwardly open recesses and U-shaped retainer members secured to the framework panels by the bolts, the panel support beams having laterally outwardly projecting flanges and the retainer members being held in clamping engagement with the outwardly projecting flanges.
 11. A slab formwork system as claimed in claim 9, including panel retainer projections extending from the downwardly open recesses into engagement with the panel support beams.
 12. A slab formwork system as claimed in claim 11, wherein the panel support beams have upwardly open recesses in the tops of the panel support beams and the panel retainer projections engage in the upwardly open recesses.
 13. A slab formwork system, comprising: formwork panels; panel support shores spaced from one another; panel support beams underlying the formwork panels and supported by the shores; the panel support beams being telescopically longitudinally adjustable to allow corresponding variation of the spacings of the shores.
 14. A slab formwork system as claimed in claim 13, wherein the panel support beams have telescopically extendable extension members and fasteners for securing the extension members relative to the panel support beams, the dropheads having bearing members for supporting engagement with the extension members.
 15. A slab formwork system, comprising: formwork panels; panel support beams; panel support shores; the shores having dropheads and the dropheads each having a first component, the first component having a prophead between an adjacent pair of the formwork panels and a second component in supporting engagement with the formwork panels; and the first and second components having mutually engaged screw threads allowing the second component to be lowered relative to the first component for releasing the formwork panels.
 16. A slab formwork system as claimed in claim 15, wherein the first component comprises a screw and a nut in threaded engagement with the screw, the prophead being at an upper end of the screw, and the second component comprises a sleeved extending around the screw and supported on the nut, first beam supports projecting from opposite sides of the sleeve and supporting the panel support beam and second beam supports projecting to opposite sides of the sleeve at right angles to the first beam supports, the slab formwork system further comprising filler beams extending between the formwork panels and supported on the second beam supports.
 17. A slab formwork system, comprising: formwork panels; panel support beams underlying and supporting the formwork panels; and shores supporting the panel support beams; the panel support beams having upwardly facing top surfaces; upwardly open, longitudinally extending recesses in the top surfaces and resiliently deformable strips of elastomeric material extending along the recesses; the formwork panels having marginal edge undersurface portions mounted on the panel support surfaces and downwardly protruding panel retainer projections embedded in the resiliently deformable strips; the formwork panels each having a pair of parallel, elongate side members, elongate intermediate members extending between and interconnecting the side members and a sheet of material supported on the side and intermediate members; and the side members having undersides formed with a longitudinally extending, downwardly open recesses; connecting clips retained in the downwardly open recesses and engaged with the support beams to secure the formwork panels to the support beams; the panel support beams being telescopically longitudinally adjustable to allow corresponding variation of the spacings of the shores; the shores having dropheads, the dropheads each having a first component forming a prophead extending between an adjacent pair of the formwork panels and a second component in supporting engagement with the formwork panels; and the first and second components having mutually engaged screw threads allowing the second component to be lowered relative to the first component for releasing the formwork panels. 